The 25-year-old won $557,000 at Roland Garros - his best performance at a major to date. He told Gazzetta dello Sport on Tuesday:
"After losing to Djokovic, I returned to Latvia with my cousin and I went to the Casino: I bet all prize money won in Paris and I lost it."
Gulbis is known for saying outlandish things. He got himself in trouble in Paris by saying women's tennis players should focus more on having kids than winning titles.
So who knows if he's telling the truth about blowing half a million dollars.
He joked about the gambling failure in an interview in the UK, but said he only lost a "percentage" of his winnings this time:
Gulbis: "I went back home for two days, I just went to..."
Reporter: "Party?"
Gulbis: "Not really party. I went a little bit to a casino to gamble away a percentage of my winnings, so I have to get it back this week."
Reporter: "Were you a winner or a loser in the casino?"
Gulbis: "I was a big loser."
Reporter: "What game were you playing?"
Gulbis: "Blackjack."
Reporter: "I love the fact that you're still maintaining this image of a maverick figure on the tour."
Gulbis: "It's not image at all."
The video: